Piezoelectric properties of PbHfO3–PbTiO3–Pb(Mg1/3Nb2/3)O3 ternary ceramics

(1 – x)Pb(Hf_1–yTi_y)O₃–x Pb(Mg_1/3Nb_2/3)O₃ (x = 0.1 ～ 0.25, y = 0.555) ternary piezoelectric ceramics were prepared using the two‐step precursor method. Morphotropic phase boundary (MPB) compositions, located at x = 0.18 ～ 0.22, were confirmed using X‐ray diffraction and by their dielectric, piezoelectric and ferroelectric properties. The optimum dielectric and piezoelectric properties were achieved for the MPB composition 0.8Pb(Hf_0.445Ti_0.555)O₃–0.2Pb(Mg_1/3Nb_2/3)O₃, with dielectric permittivity ε_r, piezoelectric coefficient d₃₃, planar electromechanical coupling k_p and Curie temperature T_C being on the order of 2800, 680 pC/N, 70% and 276 °C, respectively. Of particular significance is that the new ternary ceramics exhibit comparable piezoelectric and electromechanical properties to commercial PZT5H ceramics, but with much improved T_C, showing a potential for applications at elevated temperature. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Facile preparation and performance of novel high-TC xBi(Ni1/2Ti1/2)O3-(1-x)Pb(Zr1/2Ti1/2)O3 piezoceramics

High Curie temperature (T_C) xBi(Ni_1/2Ti_1/2)O₃-(1-x)Pb(Zr_1/2Ti_1/2)O₃ (xBNT-(1-x)PZT, BNT-PZT) piezoelectric ceramics were prepared by the conventional ceramic processing. The composition-induced morphotropic phase boundary (MPB) and its influences on structure and electrical performance were investigated. The synthesized BNT-PZT ceramics exhibit rather pure perovskite structure, and densified microstructure morphology with uniform elementals distribution in both grains and grain boundaries. With increasing the content of Bi(Ni_1/2Ti_1/2)O₃ (BNT), crystal structure of the BNT-PZT ceramics transform from tetragonal phase to rhombohedral phase, and dielectric response peaks change from narrow shape to very broad shape but all presenting dielectric frequency dispersion. The diffused and relaxation dielectric behavior can be fitted well by the quadratic law, and the Vogel-Fulcher law fitting provides additional information on the relaxation characteristic. The MPB effects are confirmed further by ferroelectric and piezoelectric properties measurements. High-T_C combined with excellent piezoelectric performance can be realized in the BNT-PZT system, which presents promising applications in geothermal exploration, aerospace and related elevated temperatures fields.     

Piezoelectric properties of new ternary Bi1/2(Na, Li)1/2TiO3–(Bi1/2K1/2)TiO3–Ba0.85Ca0.15Ti0.90Zr0.10O3 ceramics

0.852[Bi_1/2(Na_1?x Li _x )_1/2]TiO₃?C0.110(Bi_1/2K_1/2)TiO₃?C0.038Ba_0.85Ca_0.15Ti_0.90Zr_0.10O₃ (BNLT?CBKT?CBCTZ-x) new ternary piezoelectric ceramics were fabricated by the conventional solid-state method, and their piezoelectric properties as a function of the Li content were mainly investigated. A?stable solid solution with a single perovskite structure has been formed, and the depolarization temperature (T _d) of these ceramics was identified by using the temperature dependence of the dielectric loss. The T _d value of these ceramics gradually decreases, while the T _m value increases with increasing the Li content. The dielectric constant increases and the dielectric loss decreases with increasing the Li content, and an enhanced piezoelectric behavior of d ₃₃??223 pC/N and k _p??35.2?% has been demonstrated in these ceramics with x=0.06.     

Electrical properties of neodymium doped CaBi4Ti4O15 ceramics

Neodymium doped bismuth layer structure ferroelectrics (BLSFs) ceramics CaBi_4−xNd_xTi₄O₁₅ (x=0, 0.25, 0.50, 0.75) were prepared by solid-state reaction method. X-ray diffraction pattern showed that single phase was formed when x=0-0.75. The refined lattice parameters showed that a (b) axes decrease at x=0.25 and increase with more Nd³⁺ dopant. The effects of Nd³⁺ doping on the dielectric and ferroelectric properties of CaBi₄Ti₄O₁₅ ceramics are studied. Nd³⁺ dopant decreased the Curie temperature linearly, and the dielectric loss, tan δ, as well. The remnant polarization of Nd³⁺ doped CaBi₄Ti₄O₁₅ ceramics was increased by 80% at x=0.25, while more Nd³⁺ dopant decreased the remnant polarization. CaBi_3.75Nd_0.25Ti₄O₁₅ ceramics had the largest piezoelectric constant d₃₃. The structure and properties of CaBi_4−xNd_xTi₄O₁₅ ceramics showed that Nd³⁺ may occupy different crystal locations when Nd³⁺ content x is less than 0.25 and more than 0.50.     

Dielectric and piezoelectric properties of manganese‐modified PbHfO3–PbTiO3–Pb(Mg1/3Nb2/3)O3 ternary ceramics with morphotropic phase boundary compositions

High piezoelectric and electromechanical properties were reported in the PbHfO₃–PbTiO₃–Pb(Mg_1/3Nb_2/3)O₃ ternary system with morphotropic phase boundary (MPB) compositions. This work focuses on the effect of MnO₂ addition on 0.8Pb(Hf_0.443Ti_0.557)O₃–0.2PMN (0.8PHT–0.2PMN) ceramics. It was observed that the Mn acceptor modification induced a “hardening” effect in 0.8PHT–0.2PMN, with decreased piezoelectric coefficients d₃₃ and dielectric loss tan δ and a significantly increased mechanical quality factor Q_m. Moreover, the 0.2 wt% MnO₂‐doped 0.8PHT–0.2PMN ceramics exhibited good piezoelectric and electromechanical properties with d₃₃, planar electromechanical coupling k_p and Q_m being on the order of 360 pC/N, 61% and 700, respectively, showing advantages compared to those of commercial hard PZT4 ceramics, which is attractive for high power applications. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

In-situ X-ray microdiffraction analysis of local strain-field across the interface in a Pb(Zr0.52Ti0.48)O3/Ni0.8Zn0.2Fe2O4/Pb(Zr0.52Ti0.48)O3 tri-layered structure

We have performed a synchrotron X-ray microdiffraction to investigate the variation of the local strain-field across the interface in Pb(Zr_0.52Ti_0.48)O₃/Ni_0.8Zn_0.2Fe₂O₄/Pb(Zr_0.52Ti_0.48)O₃ (PZT–NZFO–PZT) tri-layered structure. In this study, we show that the in-plane lattice parameters of the NZFO lattice depend strongly on the piezoelectric strain of the PZT layer. This result explains that an electric-field-induced piezoelectric strain from the PZT layer is effectively transferred to the NZFO layer. Furthermore, the local strain persists within 20 μm away from the interface, inducing changes of magnetic responses via the inverse magnetostrictive effect.     

La掺杂SrBi4Ti4O15铁电材料性能研究

按x=0.00，0.10，0.25，0.50，0.75和1.00，采用固相烧结工艺，制备了不同La掺杂量的SrBi_4-xLa_xTi₄O₁₅的陶瓷样品. 用x射线衍射对其微结构进行了分析，并测量了铁电、介电性能.结果发现，La掺杂未改变SrBi₄Ti ₄O₁₅的晶体结构.随掺杂量的增加，样品的矫顽场(E_c)下降，剩余极化(2P_{关键词： 4-x}La_xTi₄O₁₅')" href="#">SrBi_4-xLa_xTi₄O₁₅ La掺杂 铁电性能 相变温度 弛豫铁电     

Dielectric and piezoelectric properties of barium-modified Aurivillius-type Na0.5Bi4.5Ti4O15

In this study, monophasic Ba_x(Na_0.5Bi_0.5)_1−xBi₄Ti₄O₁₅ (x=0.03, 0.06, 0.09 and 0.12) ceramics fabricated from the powders synthesized via the solid-state reaction route exhibited relaxor behavior. X-ray diffraction analysis revealed that the barium-modified Na_0.5Bi_4.5Ti₄O₁₅ ceramics have a pure four-layer Aurivillius phase structure. Dielectric properties and phase transitions were studied and are explained in terms of lattice response of these ceramics. A shift in ferroelectric–paraelectric phase transition (T_c) to lower temperatures and a corresponding increase in permittivity peak with increasing concentration of Ba²⁺ are also observed. The decrease of orthorhombicity in the lattice structure by the larger Ba²⁺ ion incorporation, indicating an approach of a and b parameters, results in lower Curie temperature. The piezoelectric activity of Na_0.5Bi_4.5Ti₄O₁₅ (NBT) ceramics was significantly improved by the modification of barium. The Curie temperature T_c and piezoelectric coefficient d₃₃ for the composition with x=0.12 were found to be 635 °C and 21 pC/N, respectively. The relationship of polarization with lattice response is discussed.     

The piezoelectric effect in Pb[(Fe1/3Sb2/3) x Ti y Zr z ]O3 ceramics

The piezoelectric properties of Pb[(Fe_1/3Sb_2/3) _x Ti _y Zr _z ]O₃ with x + y + z = 1, x = 0.1, y = 0.43–0.48 ceramics have been investigated over a broad temperature range using a resonance technique. The influence of modification of PZT normal ferroelectric synthesized near the morphotropic phase boundary by a relaxor Pb(Fe_1/3Sb_2/3)O₃ compound on its physical properties was studied. The coefficients s ₁₁, k ₃₁, and d ₃₁ were calculated from the parameters characterizing the behavior of damped harmonic oscillator in the vicinity of the piezoelectric resonance. Several anomalies of the piezoelectric coefficients have been found in the temperature range 300–600 K. Two diffuse phase transitions were observed in Pb[(Fe_1/3Sb_2/3) _x Ti _y Zr _z ]O₃. The anomaly near 530 K for y = 0.43 is responsible for the transition from the rhombohedral phase to the tetragonal one. For y > 0.44 this transition is found to be very diffuse and the coexistence of rhombohedral and tetragonal phases occurs. The observation of low piezoelectric activity confirms the existence of polar regions in Pb[(Fe_1/3Sb_2/3) _x Ti _y Zr _z ]O₃ above T _m.     

Microstructure,dielectric, and piezoelectric properties of Ce‐modified Na0.5Bi4.5Ti4O15 high temperature piezoceramics

The cerium modified sodium bismuth titanate (Na_0.5Bi_4.5Ti₄O₁₅, NBT) piezoelectric ceramics have been prepared by using the conventional mixed oxide method. X‐ray diffraction analysis revealed that the cerium modified NBT ceramics have a pure four‐layer Aurivillius phase structure. The piezoelectric activity of NBT ceramics was found significantly improved by the modification of cerium. The Curie temperature T_c, and piezoelectric coefficient d₃₃ for the NBT ceramics with 0.50 wt% cerium modification were found to be 655 °C, and 28 pC/N respectively. The Curie temperature gradually decreased from 668 °C to 653 °C with the increase of cerium modification. The dielectric spectroscopy showed that the samples possess stable piezoelectric properties, demonstrating practical potential that for high temperature applications. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Enhanced piezoelectric properties of sodium bismuth titanate (Na0.5Bi4.5Ti4O15) ceramics with B‐site cobalt modification

The piezoelectric properties of the cobalt‐modified sodium bismuth titanate (Na_0.5Bi_4.5Ti₄O₁₅, NBT) piezoelectric ceramics were investigated. The piezoelectric properties of NBT ceramics were significantly enhanced by cobalt modification. The Curie temperature T_C and piezoelectric constant d₃₃ for the 0.3 wt% cobalt‐modified NBT ceramics (NBT‐C3) were found to be 663 °C and 30 pC/N, respectively. Thermal annealing studies presented that the cobalt‐modified NBT ceramics possess stable piezoelectric properties, demonstrating that the cobalt‐modified NBT‐based ceramics are promising candidates for high temperature piezoelectric applications. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Elastic properties, thermal expansion coefficients and electronic structures of Ti0.75X0.25C carbides

Elastic properties, thermal expansion coefficients and electronic structures of Ti_0.75X_0.25C carbides (X=W, Mo, Ta, Nb, V, Hf, Zr, Cr and Al) were systematically investigated using ab initio density functional theory (DFT) calculations. The calculated elastic moduli, electronic structures and thermal expansion coefficients α(T) of pure TiC are in good agreement with experimental data and other DFT calculations. Based on a phenomenological formula, the trends of elastic properties and ductile/brittle behavior of Ti_0.75X_0.25C were analyzed. It was found that alloying elements W, Mo, Ta, Nb, V and Hf can increase elastic moduli, while Zr, Cr and Al reduce moduli. The nearly free electron model and Debye approximation were applied in the evaluation of α(T). The anharmonic effect was taken into account by including volume-dependent elastic moduli and Debye temperature. Results show that alloying additions of 3d V, 4d Zr and Mo slightly reduce α(T), while 3d Cr increases α(T), Al, 4d Nb, 5d Hf and W almost keep α(T) unchanged in Ti_0.75X_0.25C at high temperatures. The electronic structures of Ti_0.75X_0.25C were calculated and analyzed, and the electronic density of states was used to interpret variations of elastic properties and ductile/brittle behavior induced by alloying additions.     

Structural, dielectric relaxation and piezoelectric characterization of Sr substituted modified PMS-PZT ceramic

Pyrochlore phase free [Pb_0.94Sr_0.06] [(Mn_1/3Sb_2/3)_0.05(Zr_0.53Ti_0.47)_0.95] O₃ ceramics has been synthesized with pure Perovskite phase by semi-wet route using the columbite precursor method. The field dependences of the dielectric response and the conductivity have been measured in a frequency range from 50 Hz to 1 MHz and in a temperature range from 303 K to 773 K. An analysis of the real and imaginary parts of the dielectric permittivity with frequency has been performed, assuming a distribution of relaxation times. The scaling behavior of the dielectric loss spectra suggests that the distribution of the relaxation times is temperature independent. The SEM photographs of the sintered specimens present the homogenous structures and well-grown grains with a sharp grain boundary. The material exhibits tetragonal structure. When measured at frequency (100 Hz), the polarization shows a strong field dependence. Different piezoelectric figures of merit (k_p, d₃₃ and Q_m) of the material have also been measured obtaining their values as 0.53, 271 pC/N and 1115, respectively, which are even higher than those of pure PZT with morphotropic phase boundary (MPB) composition. Thus the present ceramics have the optimal overall performance and are promising candidates for the various high power piezoelectric applications.     

Lanthanum-doped Bi4Ti3O12 ceramics prepared by high-pressure technique

We present an effective way in this paper to increase the density of lanthanum doped bismuth titanate ceramics, Bi4-xLaxTi3O12 (BLT), thereby significantly improving the performance of the BLT ceramics. Dense BLT ceramicses, Bi4-xLaxTi3O12 (x = 0.25, 0.5, 0.75, 1.0), are prepared by using nanocrystalline powders fabricated by a-gel method and high-pressure technique. The microstructures of the BLT ceramicses prepared separately by conventional-pressure and high-pressure techniques are investigated by using x-ray diffraction and transmission electron microscope. The influence of La-doping on the densification of bismuth titanate ceramics is investigated. The experimental results indicate that the phase compositions of all samples with various lanthanum dopings sintered at 900°C possess layer-structure of Bi4Ti3O12 . The green compacts are pressed under 2.5 GPa, 3.0 GPa, 3.5 GPa and 4.0 GPa, separately. It is found that the density of BLT ceramics is significantly increased due to the decreasing of porosity in the green compacts by high-pressure process.     

Influence of fabrication processing on phase transition and electrical properties of 0.8Pb(Zr1/2Ti1/2)O3–0.2Pb(Ni1/3Nb2/3)O3 ceramics

The binary system of 0.8Pb(Zr_1/2Ti_1/2)O₃–0.2Pb(Ni_1/3Nb_2/3)O₃ ceramics were synthesized by conventional mixed oxide and columbite method. X-ray diffraction analysis demonstrated the coexistence of both the rhombohedral and tetragonal phases for the columbite prepared sample. Rhombohedral to tetragonal phase transition for columbite method was different compared with those of the mixed oxide method. The permittivity shows a shoulder at the rhombohedral to tetragonal phase transition temperature T_Rho–Tetra = 195 °C, and then a maximum permittivity (36,000 at 10 kHz) at the transition temperature T_m = 277 °C on ceramics prepared with the columbite method. However, piezoelectric coefficient (d₃₃) was measured to be 282 pC/N for the conventional method and higher than the columbite method. The results were related to the phase compositions and porosity of the ceramics.     

Transparent ferroelectric ceramics PbMg1/3Nb2/3O3-xPbZr0.53Ti0.47O3: Dielectric and electro-optical properties

Lanthanum-free high-transparency ferroelectric ceramics PbMg_1/3Nb_2/3O₃?xPbZr_0.53Ti_0.47O₃ (PMN-xPZT) have been prepared for the first time by a two-stage sintering method. The dielectric and electro-optical properties of the PMN-xPZT ceramics of different compositions, with the values of x both far from the morphotropic phase boundary (x = 10, 16, 23%) and close to it (x = 33%), have been studied. It has been shown that, in compositions lying closer to the morphotropic phase boundary (x = 23 and 33%), one observes, with no electric field applied, a first-order phase transition to a macrodomain ferroelectric phase, whereas the compositions far from the boundary (x = 10, 16%) persist in the relaxor cubic phase down to the low-temperature domain. It has been found that, in the ceramic with x = 33%, the quadratic electro-optical coefficients have at high temperatures (T > 340 K) the largest value among the relaxor systems, which expands the temperature interval of applicability of these solid solutions in industry.     

Enhanced ferroelectric and piezoelectric properties in La-modified PZT ceramics

The effect of lanthanum (La) doping on ferroelectric and piezoelectric properties of lead zirconate titanate (PZT) sample has been investigated. Pb_1?x La _x Zr_0.52Ti_0.48O₃ ceramics with x = 0.00, 0.02, 0.04, 0.06 and 0.10 were prepared by the sol–gel technique. Raman and Fourier transforms infrared spectroscopy have been employed to understand the structural modification due to ionic size mismatch. Raman spectra show the existence of both rhombohedral and tetragonal crystal symmetries. It also shows the dielectric relaxation with increase in La concentration in the sample. The increase in lattice strain due to La doping increases the remnant polarization and coercive field. The linear piezoelectric coefficient increases with the increase in La concentration. It reveals that La-substituted PZT is a better candidate for piezoelectric sensor applications as compared to that of PZT.     

Piezoelectric, dielectric and magnetic properties of (1-x)Pb[Zr, Ti, (Mg1/2W1/2), (Ni1/3Nb2/3)]O3+x(Ni, Co, Cu)FeO4 composites

The phase structure, microstructure, piezoelectric properties, dielectric characteristic and the ME effect of magnetoelectric Pb[Zr_0.23Ti_0.36+0.02(Mg_1/2W_1/2)+0.39(Ni_1/3Nb_2/3)]O₃ (PZT)+xNi_0.8Co_0.1Cu_0.1Fe₂O₄ (NCCF) composite ceramics were prepared by the conventional solid state reaction method. The structural analysis of both the constituent phases and their composites was carried out by X-ray diffraction, energy dispersive spectrometry and scanning electron microscopy. The results showed cubic spinel structure for ferrite phase and tetragonal perovskite structure for ferroelectric phase. The piezoelectric constant, dielectric constant, Curie temperature, remanent polarization and coercive electric field decreased with increase of ferrite content. The coercive field strength, saturation magnetization and remanent magnetization increased with increasing ferrite content.     

Uniaxial stress dependence of ferroelectric properties of xPMN-(1–x)PZT ceramic systems

Effects of uniaxial compressive pre-stress on the ferroelectric properties of ceramics in the PMN-PZT system are investigated. The ceramics with a formula xPb(Mg_1/3Nb_2/3)O₃-(1-x)Pb(Zr_0.52Ti_0.48)O₃ or xPMN-(1-x)PZT when x=0.0, 0.1, 0.3, 0.5, 0.7, 0.9, and 1.0 are prepared by a conventional mixed-oxide method. The ferroelectric properties under the uniaxial compressive pre-stress of the PMN-PZT ceramics are observed at the stress levels up to 13 MPa using a compressometer in conjunction with a modified Sawyer–Tower circuit. It is found that with increasing compressive pre-stress levels the area of the ferroelectric hysteresis (P–E) loops, the saturation polarization (P_sat), the remanent polarization (P_r), and the coercive field (E_c) decrease. These results are interpreted through the non-180° ferroelastic domain-switching processes. Finally, the calculated differential permittivity for all the xPMN-(1-x)PZT ceramics, except for 0.5 PMN-0.5 PZT, decreases with increasing applied stress. PACS 77.22.Ch; 77.84.Dy     

Ferroelectric phase transition of Nb-doped Bi<Subscript>3.25</Subscript>La<Subscript>0.75</Subscript>Ti<Subscript>3</Subscript>O<Subscript>12</Subscript> ceramics

Bi_3.25La_0.75Ti_3-yNb_yO₁₂ (y=0.0, 0.03, 0.09, 0.15, 0.21) were synthesized using the solid-state reaction method. The effects of Nb doping on ferroelectric properties were studied through dielectric and P-E measurements. The value of P_r increases with increasing Nb content. Bi_3.25La_0.75Ti_3-yNb_yO₁₂ ceramics exhibit a maximum remanent polarization of P_r=27 μC/cm² at an Nb content of y=0.09. These results indicate that Nb doping can improve the ferroelectric properties of BLT ceramics. The Curie temperature, T_c, decreased with increasing Nb-content, and the ferroelectric phase transition of BLTNy is a second-order transition without thermal hysteresis. PACS 77.55.+f; 77.80.-e; 77.22.Jp